The present invention relates generally to a new and useful apparatus and method for packaging food products, and more specifically, to improved devices and methods for more economic packaging of sausage products in tubular food casings.
In the manufacture of sausage products, meat emulsion is prepared from communited meat together with fillers, seasonings, spices, etc. A tubular food casing, such as nonedible cellulose, is loaded onto the stuffing horn of a filling machine and stuffed with the meat emulsion. In the case of small sausage products, like frankfurters, the filled casings are twisted, tied or clipped into suitable links at predetermined intervals and further processed. For larger sausage products, like bologna, salami, and the like, the meat emulsion is introduced into larger, heavier walled fibrous type casings and formed into chubs or lengthy individual sausage sticks.
In preparing large diameter sausage products, like bologna, an important consideration is the maintenance of accurate size control over the entire length of the sausage stick. It is important that the diameter of large sausage products be controlled very carefully so that meat packers are able to cut the sausage into slices of predetermined thickness and diameter for prepackaging. The objective is to have a given number of slices weigh precisely a predetermined amount for each package. In other words, a given number of slices should weigh exactly one pound or some other preselected weight.
A further important consideration, in the preparation of large diameter sausage products for prepackaging, concerns end portions. Sticks, having either tapered ends or enlarged bulbous ends, provide poor yields. The end portions of a bologna, for example, which are either undersized or oversized can result in the loss of up to five inches of meat from each end of the sausage product, since off-spec slices cannot be used for prepackaged meat products. In addition to forming packages which fail to meet required preselected weight standards, sliced product prepared from sticks having bulbous ends cannot be enclosed in display packages.
As a result of the problem of filling equipment forming packages with ends which result in substantial waste, meat processors and equipment manufacturers are constantly striving to improve both operations and machines that affect finished package yield. For example, U.S. Pat. No. 3,621,513 discloses a stuffing apparatus which is capable of forming sausages with a variety of end portion configurations, including tapered, elongated ends and taut ends whose rounded end portion have been reduced and minimized. To prepare filled casings with taut, nontapered ends, when the flow of emulsion is terminated a dished shaped platen is needed to compress and aid in shaping the trailing end of the filled casing by moving downstream from the stuffing horn outlet against the filled casing. Simultaneously, an internal casing presizer engaged with the stuffing horn is maintained in an expanded, operative mode to restrain the release of unfilled casing from the horn. Consequently, increased pressure is exerted against the trailing end of the filled casing by the dished platen. While in this position a clipper unit is actuated to close the casing.
Filled casings with tapered ends may also be prepared with the apparatus of U.S. Pat. No. 3,621,513. In this regard, elongated ends are formed by contracting the casing presizer to release unfilled casing from the horn after operation of the food pump is terminated. The dished platen is then moved downstream from the stuffing horn stripping casing from the horn while permitting some of the food emulsion to flow upstream into the unfilled loose casing where the casing is clipped. Accordingly, the methods and apparatus of U.S. Pat. No. 3,621,513 are dependent on a multiplicity of components, including concentric sleeve casing presizer, casing brake, emulsion stopping ring, dished platen, casing clippers, etc.
U.S. Pat. No. 4,562,617 discloses means for preparing dimensionally uniform filled food casings with nontapered ends. The uniform filled casings are prepared by introducing with the food product "a closing piece" inside the casing at the terminal ends. The closing pieces occupy interior space which otherwise would have been filled with meat emulsion to produce tapered ends. U.S. Pat. Nos. 4,028,775 and 4,160,305 also relate to apparatus and methods of inserting sizing discs into tubular casings.
U.S. Pat. No. 3,454,980 to H. G. Washburn and U.S. Pat. No. 3,553,768 to G. M. Wilmsen also disclose means for sizing control in stuffing operations. Devices disclosed therein rely on tubular sleeves for improving sausage diameter uniformity. Variations in sausage diameter are corrected by means of an annular ring which engages a conical face on the edge of the stuffing horn to control the rate of casing feed off the horn. Thus, to enlarge undersized sausage to a predetermined diameter during the stuffing cycle, pressure of the annular ring against the casing on the edge of the stuffing horn is increased in order to increase the friction and slow the rate at which unfilled casing is released from the horn. Similar adjustments are made in correcting for oversized diameters during the stuffing cycle, except that fricitonal pressure against the casing on the horn is reduced allowing the empty casing to be released more freely from the horn.
According to U.S. Pat. No. 3,454,980 variations in sausage diameter are constantly monitored and automatically corrected by a pneumatic sensing device in combination with a fluid motor, the latter of which controllably adjusts the frictional pressure applied to the casing at the conical edge of the stuffing horn by lateral movement of the annular ring. Although the Washburn and Wilmsen devices are effective in achieving accurate size control, they do not provide means for restricting the backflow of food emulsion over the stuffing horn during the closure cycle. In addition, no specific means are provided for making substantially flattened terminal ends for minimizing potential waste and lower product yield.
A further sizing apparatus is disclosed by Niedecker in U.S. Pat. No. 3,748,690 wherein an axially slideable snubbing element on the stuffing horn is displaced forwardly downstream after the completion of the filling cycle to push or release unfilled casing from the horn when the clipper gates are actuated. Like many of the foregoing filling machines, the methods of Niedecker fail to provide means for minimizing tapering or enlarged rounded ends. Accordingly, there is need for a sausage stuffing apparatus with improved sizing control means for making filled casings with terminal end portions which are neither tapered nor enlarged, such improved means not being dependent either on the introduction of special casing inserts or multiple machine components.